Portable chain saw with antivibration handle

ABSTRACT

In a portable chain saw powered by a reciprocating engine, vibrations from the engine to the handle grasped by the operator(s) are absorbed by forming the handle with a core which is rigidly attached to the chain saw body and a sheath which surrounds the handle in spaced relation and held relatively to the core by a spacer of yieldable material, such as one or more pieces of rubberlike material or corrugated leaf springs or radial coiled expansion springs which engage both the core and the sheath, the latter being grasped by the operator.

United States Patent lnventor Alfonso Lange Dorpleldstrasse 8, 2000Hamburg 52, Germany Appl. No. 852,235 Filed Aug. 22, 1969 Patented Nov.16, 1971 Priority Feb. 20, 1969 Germany P 19 08 451.6

PORTABLE CHAIN SAW WITH ANTIVIBRATION HANDLE 6 Claims, 16 Drawing Figs.

US. Cl

Int. Cl B27b 17/02 Field of Search 143/ 32' [56] References Cited UNITEDSTATES PATENTS 2,610,657 9/1952 Kiekhaefer 1,800,254 4/1931 Holmes786,050 3/1905 Richwood.....

Primary E.raminer-- Donald R. Schran Allorney-Milmore & Cypher 143/32l6/ll6X 173/162 ABSTRACT: In a portable chain saw powered by areciprocating engine, vibrations from the engine to the handle graspedby the operator(s) are absorbed by forming the handle with a core whichis rigidly attached to the chain saw body and a sheath which surroundsthe handle in spaced relation and held relatively to the core by aspacer of yieldable materiaL such as one or more pieces of rubberlikematerial or corrugated leaf springs or radial coiled expansion springswhich engage both the core and the sheath, the latter being grasped bythe opera- PAIENTEDumv 16 I971 SHEET 1 OF 4 lnren/ar Alf nse Lm 6} 1 695 6,

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PORTABLE CHAIN sAw wmi ANI'IVIBRA'IION HANDLE The invention relates toportable chain saws driven by a motor having a reciprocating piston, andis particularly concemed with a handle, to be grasped by the operator,which is rigidly attached to the body of the chain saw and isconstructed to dampen the vibrations from the motor to the operator.

Known handles of such portable, powered chain saws have been providedwith cushioning coverings of elastic material. If the dampening of thevibrations is to be effective, a very pliable or soft covering must beused; however, such a covering greatly reduces the transmission ofcontrolling motions from the hands of the operator to the saw. Thedamping effect of the covering is greatly reduced whenever the operatorapplies a force or a compression of the covering to hold the saw or toalter the position or direction of the saw. Thus, a compressive forceapplied in one direction severely reduces damping in that direction.Moreover, such a.covering detracts from the capability of guiding thesaw, since the forces transmitted by the long supporting andchain-guiding part of the saw body or frame to the covering act toproduce vibratory motions which are lateral to the said guiding part andact through a long lever arm, and result in a tilting tendency of thesaw relatively to the soft covering grasped by the operator.

It was proposed (US. Pat. No. 3,409,056, Nov. 1968) to attach the handleat its ends to the chain saw body by vibrationdamping bushings. However,it has not been feasible to obtain a proper balance between therequirements of making such bushings sufficiently flexible to dampen thevibrations effectively and sufficiently stifi to permit the saw to beguided reliably. Further, such bushings are subject to rapid failure byfatigue.

The vibrations transmitted from the motor unit to the operator whencushioning coverings or bushings of sufficient stiffness for effectiveguidance of the saw are used, according to known constructions, inflicthealth damages to the operator and greatly reduce his endurance inmanipulating the powered chain saw.

The present invention overcomes the above-noted difficulties inproviding a handle construction which, while providing an effectivedamping of the vibrations reaching the hand(s) of the operator, permitsthe saw to be guided reliably as to position and angle of attack againstthe workpiece.

In summary, according to the invention, the body of the chain saw (onwhich the motor unit and chain-guiding parts are fixed) has handle meanswhich includes a core fixed rigidly (at one or preferably both ends) tothe body, a sheath which surrounds the core in spaced relation and ismovable relatively thereto in all radial directions, and a spacer meansof elastic material interposed between and in expansive relation to boththe core and the sheath, the latter being adapted to be grasped by thehand of the operator. The term radial directions" means radialrelatively to the axis of the core, which may include several angularlyrelated portions.

The yieldablc spacer means acts to absorb a significant part of thevibrations, while positioning the core relatively to the sheath, topermit good guidance of the saw relatively to its workpiece. Such spacermeans may take any of or a combination of several forms, such as one ormore bodies of elastic, rubber or rubberlike bodies, leaf springs whichare corrugated, or radially disposed expansion springs oriented in aplurality of radial directions and acting between the core and thesheath.

The advantage of the construction according to the invention residesprincipally in that the core, which is rigidly attached to the saw body,is connected to the graspable sheath only by the yieldablc spacer means,and that the said spacer means is not pressed or contracted by the handsof the operator, which pressing would cause contraction in certaindirections and either affect guidance or increase transmission ofvibrations in the direction in which pressure is applied. A firm graspby the hand(s) on the sheath, therefore, has no cffeet on the conditionof the yieldablc spacer means, and these spacer means are aflected onlyby the steering movements and the vibrations of the motor. Moreover, areliable guidance of the chain saw is insured, because the graspablesheath can be extended in length, whereby torque can be easilytransmitted from the sheath to the core and, hence, to the chain sawbody, whereby the position and direction of movement of the saw can becontrolled by the operator.

One embodiment of the yieldablc spacer means is a hoselike, tubularpiece formed of rubber or a synthetic, rubberlike material extendingsubstantially the full length of the sheath. In this embodiment thecross sections of the facing surfaces of the core and sheath arepreferably circular.

In another embodiment, the spacer means can consist of segments (e.g.,elastic rubber or rubberlike material or metallic springs) spacedapart'along the length of the sheath.

In another embodiment, the spacer means may be a plurality of continuousor of axially spaced segments of solid or tubular elements positionedwithinlongitudinal recesses formed by radial walls on the sheath or onthe core, e.g., longitudinal ribs extending radially outwardly from thecore.

In another embodiment, the yieldablc spacer means are formed by leafsprings, which may be formed of corrugated sheet metal and extend (inthe direction transverse to the corrugations) either parallel to theaxis of the core or around it. In either case alternate rugations pressagainst the core and the others press against the sheath. The leafsprings may, especially when they surround the core, be segmented andpositioned in axially spaced relation.

Moreover, in still other embodiments, the spacer means can take the formof coiled expansion springs, which extend in different radial direction,each spring pressing outwardly against the sheath and inwardly againstthe core. The several springs, having axes in different radialdirections, are arranged to produce an elastic force centering the axisof the core relatively to that of the sheath, and some of these springsmay be displaced along the axis of the core, as when their axes wouldotherwise lie in the same transverse plane. These coiled springs may besecured in sockets, e.g., formed in the core and providing abutments.When the core is formed of a tubular piece (having a hollow interior)the sockets may be formed by smaller, tubelike guides which are fastenedto the wall of the core. Preferably these coiled springs have lengthswhich are large in relation to the diameter of the core, and thereforedeep sockets are preferred.

The coiled springs may be provided with caps which engage the innersurface of the sheath and are slidable along said surface, toaccommodate relative axial movements between the core and the sheath,the inner ends of the springs being positioned by the above-mentionedsockets in the core.

The invention will be further described with reference to theaccompanying drawings, showing various embodiments by way ofillustration, wherein:

FIG. 1 is a plan view of a chain saw according to the invention;

FIG. 2 is a front elevation of the saw of FIG. 1;

FIG. 3 is a front elevation of the principal, transverse handle, to anenlarged scale, parts appearing in section;

FIG. 4 is a transverse section taken on the line 4-4 of FIG.

FIG. 5 is a view, principally in section on the broken section line 5-5of FIG. 6 and corfesponding to FIG. 3, showing a second embodiment ofthe handle;

FIG. 6 is a transverse section taken on the line 6-6 of FIG.

FIG. 7 is a view corresponding to FIG. 3 of part of a handle, showing athird embodiment;

FIG. 8 is a transverse section taken on the line 8-8 of FIG. 7;

FIG. 9 is a view, partly in section, corresponding to FIG. 3, of a partof a handle, showing a fourth embodiment;

FIG. 10 is a transverse section taken on the line 10-10 of FIG. 9;

FIG. 11 is an elevation of a longitudinal or pistol-grip handle,illustrating a fifth embodiment employing radially acting coiledexpansion springs as the yieldable spacer means;

FIG. 12 is a transverse section taken on the line 12-12 of FIG. 11;

FIG. 13 is a section taken on the longitudinal line 13-13 of FIG. 12;

FIG. 14 is an elevation of a handle, corresponding to FIG. 3, showing atransverse handle according to a sixth embodiment, having a tubularcore;

FIG. 15 is a transverse section taken on the line 15-15 of FIG. 14; and

FIG. 16 is a section taken on the longitudinal line 16-16 of FIG. 15.

Referring to FIGS. 1 and 2, the portable, powered chain saw comprises abody or frame 17 which includes a projecting part 18, rigidly securedthereto, for guiding a saw chain, indicated by the chained line 19 andhaving saw teeth. This part includes at its outer end an idling wheel 20and (not shown), a driving gear which is mounted on the body. Thisdriving gear is coupled to the output shaft of a motor 21, such as aninternal combustion engine having a reciprocating piston, movable, forexample, on the axis 22. The chain saw has handle means, which includesa principal handle 23, extending more or less transversely to thelongitudinal direction of the part 18, usually at a small angle to theperpendicular to the length of the said part 18, and a pistol-griphandle 24 at the rear, more or less parallel to the direction of thesaid part and either in the same plane or offset therefrom. Thesehandles are rigidly secured to the body 17 by their cores.

As appears in FIGS. 1-4, the transverse handle 23 includes a core 25,such as a solid or, preferably, tubular member as shown, attachedrigidly at both of its ends to the body 17. This core is advantageouslyformed in a plurality, e.g., four, angularly related portions, as shownin FIGS. 2 and 3. A sheath 26, extending over at least two of saidportions and the connecting curved part, is situated in radially spacedrelation to the core to provide an intervening space within which thereis a plurality of axially spaced rings 27 of rubber or syntheticmaterial having elastic properties. These rings press against both thecore and the sheath, whereby the sheath is movable relatively to thecore in all directions which are radial to the core. The rings 27 can befixed to the core at intervals to leave intervening spaces 28 and thesheath can be formed as a plurality of longitudinal sections, such as 26and 26, joined by weldments 29, as appears in FIG. 4. The assembledsheath can thereafter be covered with a suitable gripping material 30,such as synthetic rubber hose which contract when heated and is slippedover the assembled handle before the ends of the core 25 are attached tothe saw body.

Instead of the spaced rings 27 it is possible to use a continuouselastic body, also tubular in shape, the spaces 28 being theneliminated; or the spacer means may consist of a plurality of ringssituated close together so as to eliminate the spaces 28.

The damping action of the yieldable spacer means can be varied to thedesired degree by a choice of the resiliency of the elastic material, ofthe radial distance between the core 25 and the sheath 26, the lengthsof the rings 27, and the lengths of the intervals 28.

According to the second embodiment shown in FIGS. and 6, the handle core25a, which is rigidly secured to the body of the chain saw, is solid andhas a cross section that provides a plurality, such as four, radialwalls 31 which are angularly related and extend longitudinally, toprovide intervening longitudinal recesses. A longitudinal, solid (ortubular, hoselike) spacer body 27a is laid into each of these recesses,in abutting relation to both the core 25a and a sheath 26a, which has acomplementary section 260' attached by weldments 29a. Advantageously,these elastic spacer bodies 271: have dimensions, when not stressed,slightly greater than the spaces containing them, so that they (like therings 27) are under compression when the sheath 26a is attached;however, this is optional.

It is evident that the circle enclosing the walls 31 has a diameter lessthan the interior of the sheath, whereby these parts are relativelymovable in all radial directions.

To facilitate attaching the core to the body of the saw, tubularsections 32 can be attached by sliding them over the ends of the coreand welding.

In the third embodiment of FIGS. 7 and 8 the handle core 25b and sheath26b, 26b, are separated by a plurality of, such as four, longitudinalcorrugated leaf springs 27b, alternate rugations of which engage thecore and sheath. The springs 27!), which constitute the yieldable spacermeans, may optionally be shaped so as to be slightly deformed when thesheath sections are joined by the weldments 29b. To prevent displacementof the springs circumferentially about the core, the latter may beformed with a longitudinal groove 33 for each spring, of width toaccommodate one spring. Relative longitudinal motion between the springsand the core is prevented by abutment of the spring ends with the endsof these grooves; however, the springs can slide both circumferentiallyand longitudinally relatively to the sheath. As shown, the core 25b maybe tubular. It is understood that the handle is only partly shown inFIG. 7, and the core ends are rigidly secured to the saw body.

The fourth embodiment, shown in FIGS. 9 and 10, differs from the thirdembodiment principally in that the corrugated leaf springs 27c extendcircumferentially about the tubular core 25c and are bands which arespaced apart along the length of the core. Again, alternate rugationspress against the core 250 and the sheath, which includes sections 260and 26: joined by weldments 29c.

FIGS. 11-13 show a fifth embodiment of the handle, and illustrates it asapplied to the pistol-grip handle 24. The handle includes a solid core25d, which is connected rigidly at its ends to the rear of the saw body17, and a sheath 26d, 26d having weldments 29d which sheath is spacedradially outwardly from the core. The core and sheath are relativelypositioned by a plurality of coiled compression springs 27d, 27d, whichconstitute the yieldable spacer means. These springs are suitablypositioned; for example, their inner ends can lie within sockets 34closed at their inner ends to provide abutments. A pair of verticalsprings 27d can be mounted coaxially at each of several positions alongthe core, while a pair of transverse springs 27d is mounted coaxially atvarious other positions. This staggering of the vertical and transversesprings permits the sockets to extend deeply into the core, wherebylonger coiled springs can be used then without staggering. Optionallybut preferably the springs have length to be under compression when thehandle is assembled.

Although only one row of vertical springs 27d and one row of transverseor horizontal springs 27d were shown, it is evident that the number ofrows and the angular relations can be varied, as by using two or threeparallel rows, and/or by inclining the springs at 60 to the direction ofanother spring.

The sixth embodiment, shown in FIGS. 14-16 as applied to the principaltransverse handle 23, also uses coiled springs 27c as the yieldablespacer means, but uses a tubular core 25. To provide sockets, there aresmaller tubular guides 35, which are secured, as by welding, to the wallof the core at openings therein and extend radially inwards toward animperforate portion of the opposite core wall. Successive guides 35along the length of the core have different orientations, e.g., apart asshown. Each guide contains a coiled expansion spring 27e whichpreferably carries at its outer end a cap 36 having a positioning studextending into the coil and a smooth, preferably rounded outer surfacecapable of sliding motion along the inner surface of a sheath 26e, 26c,which includes a weldment 29e. The springs 27c preferably but optionallyhave lengths to be in compression when the handle is assembled.

It is evident that the caps 36 permit free sliding motion of the sheathrelatively to the axes of the coiled springs. Relative longitudinalmotion occurs in one handle portion (e.g., part 37) when relative radialvibrations between the sheath and core occur at another part which isangularly disposed (e.g., the part 38). It may be noted that thisrelative longitudinal motion is possible by deformation of the spacerbody 27, 27a or 27d and by sliding motion of the sheath relatively tothe spacer body 27b or 270 in the earlier embodiments.

I claim as my invention:

1. In a portable power chain saw which comprises a saw chain. body meansincluding a part for supporting and guiding said chain, a motor unitmounted on said body means and including a reciprocable piston connectedto drive said chain, and handle means, the improvement wherein saidhandle means include:

a. a core rigidly attached to said body means,

b. a stilT sheath adapted to be grasped by hand which surrounds saidcore in spaced relation to provide an intervening space and which ismovable relatively to the core in all radial directions, and

c. yieldable spacer means situated within said space for positioning thecore relatively to the sheath, said spacer means comprising a pluralityof elongated elastic elements situated at positions spaced along thelength of the core and having their axes angularly related, each elementbeing in abutment at one end thereof with the core and at the other endthereof with the sheath,

whereby vibrations from the motor acting on the core are partly absorbedby the spacer means.

2. A chain saw according to claim ll wherein said core is formed toprovide a plurality of sockets having abutments at their inner ends, andeach of said elongated elements has one end thereof situated within oneof said sockets in abutting relation to the abutment of the respectivesocket.

3. A chain saw according to claim 2 wherein said core is tubular inform, and each of said sockets includes a substantially radiallyextending tubular guide which is fixed to the tubular core.

4. A chain saw according to claim 2 wherein each of said elongatedelements has a cap interposed between the outer end of the element andthe sheath and secured to the element, said caps being slidablerelatively to the sheath.

5. A chain saw according to claim 1 wherein said elastic expansionelements are tubular in shape.

6. A chain saw according to claim 5 wherein said tubular expansionelements are coiled springs.

a a a a a

1. In a portable power chain saw which comprises a saw chain, body meansincluding a part for supporting and guiding said chain, a motor unitmounted on said body means and including a reciprocable piston connectedto drive said chain, and handle means, the improvement wherein saidhandle means include: a. a core rigidly attached to said body means, b.a stiff sheath adapted to be grasped by hand which surrounds said corein spaced relation to provide an intervening space and which is movablerelatively to the core in all radial directions, and c. yieldable spacermeans situated within said space for positioning the core relatively tothe sheath, said spacer means comprising a plurality of elongatedelastic elements situated at positions spaced along the length of thecore and having their axes angularly related, each element being inabutment at one end thereof with the core and at the other end thereofwith the sheath, whereby vibrations from the motor acting on the coreare partly absorbed by the spacer means.
 2. A chain saw according toclaim 1 wherein said core is formed to provide a plurality of socketshaving abutments at their inner ends, and each of said elongatedelements has one end thereof situated within one of said sockets inabutting relation to the abutment of the respective socket.
 3. A chainsaw according to claim 2 wherein said core is tubular in form, and eachof said sockets includes a substantially radially extending tubularguide which is fixed to the tubular core.
 4. A chain saw according toclaim 2 wherein each of said elongated elements has a cap interposedbetween the outer end of the element and the sheath and secured to theelement, said caps being slidable relatively to the sheath.
 5. A chainsaw according to claim 1 wherein saId elastic expansion elements aretubular in shape.
 6. A chain saw according to claim 5 wherein saidtubular expansion elements are coiled springs.